Part of [Scott’s] design relies on some reverse engineered Blackberry screens we showed you a while back. He has constructed a small control panel for his apartment, which incorporates one of the aforementioned Blackberry screens, along with 10 tactile switches and a PIR sensor. The panel is built to be mounted in a wall or as a standalone unit, allowing him to control various lights and appliances throughout his home.

[Scott] spent a lot of time working on the communications protocol and UI for his control panel. As it sits now, the panel takes advantage of a VNC-like protocol he designed, which allows him to interact with a Java application residing on his desktop computer.

Things are looking awesome so far, and [Scott] already has a handful of improvements planned for the near future. We can’t wait to check it out when it’s finished.

If I wanted to have one of these mounted in a wall, I’d probably want to run the power from a reasonable distance away, and that would mean using something higher voltage than 5V or 3.3V. This is exactly why PoE is 48V. And if I wanted to (eventually, hopefully) have more than just a couple of these, I’d need some kind of RS232 hub – having an ethernet switch serves that purpose. So I went with PoE.

Then again, it’s possible I just wanted to be able to ping an AVR. :) Also, I’ve been looking at using the xPL support in MisterHouse, but for now, I’m just using my cobbled-together Java code.

This rivals some early commercial builds I have installed. Scott has taken homehacked automation a notch up by what he’s combined. Yes, it’s not a production ready revision. But- the direction he’s going by using a COTS display and POE makes this worth careful study.

With an interesting expansion- A slight bit of Hackery on oh- WRT54 etc level wireless routers might make this detachable from the hardwired backbone. Power only being needed at that point.

That’s because there are a LOT of places we sit in the house that may not have backbone hardwired to them, but that do have power.

I’ve actually consider doing something with a wifi module like the RN-131C, and powering it from the AC line. It gets pretty expensive pretty fast, but you could even do something with WPS to get it authenticated on a secure wireless network.

If I do something like this, it’ll probably be a remote-control for a dimmable florescent ballast or something. My problem is that I’m in a rented apartment, so I can’t run cat5 cable everywhere I want it.

Forgive me if I didn’t see it on the article itself, but is Scott using proper PoE, or a home-rolled solution? The circuit kind of looks like he’s regulating down the +48v, but I could be wrong. Could you plug this into an number of cheap, old, Cisco PoE switchs (for example) and have it operate?

Yep. IEEE 802.3af-2003.
In my case, I’m actually using a Linksys SRW224P i got from ebay, but any standard-compliant switch should work. Be aware that is some non-802.3af equipment out there – Cisco used to have their own PoE standard from before 2003.

PoE is both a CONCEPT and a SET of often incompatible “STANDARDS” that were never properly coordinated. In a ideal world, designers would craft such things so the worst-case event is simple does not operate. In the arena of Hackerdom- we’re our own oversight. Designing PoE with a mindset of never knowing what will plug into it or what it will be plugged into is a Very Good Idea. That lowers the risk of very sad smoke releases.

ANYTHING past the crudest prototypes we build “should” have a reverse polarity crowbar diode across it’s dc input plus MOV’s to clamp surges. How much is the cost difference for those parts Vs a total project loss? Add in the risk to connected gear getting smoked by a power event?

“Be careful, but not too Careful” has exceptions where device or human safety risks warrant such consideration.